TypeScript Best Practices for Modern Developers
Discover essential TypeScript patterns and practices that will help you write more maintainable and type-safe code.
TypeScript Best Practices for Modern Developers
For development teams who want to reduce runtime errors by 60% and improve code maintainability, TypeScript provides the type safety needed for large-scale applications. Having used TypeScript across multiple production applications, including and , I've learned which practices deliver the most value.
TypeScript has become the standard for building large-scale JavaScript applications. Here are some best practices to follow based on real-world experience:
Type Safety First: Define Types Early
Always define types for your functions and components. This catches errors at compile time rather than runtime:
interface UserProps {
name: string
age: number
email: string
}
const User: React.FC<UserProps> = ({ name, age, email }) => {
return <div>{name} - {age}</div>
}Use Strict Mode: Enable All Strict Checks
Enable strict mode in your tsconfig.json to catch more potential errors:
{
"compilerOptions": {
"strict": true,
"noUnusedLocals": true,
"noUnusedParameters": true,
"noImplicitReturns": true,
"noFallthroughCasesInSwitch": true
}
}Interfaces vs Types: When to Use Each
Use interfaces for object shapes and types for unions/primitives:
// Interface for object shapes (can be extended)
interface ApiResponse {
data: User[]
status: number
}
// Type for unions and primitives
type Status = 'loading' | 'success' | 'error'
type ID = string | numberRule of thumb: Use interfaces for objects you might extend, types for unions and computed types.
Avoid Any Type: Use Unknown Instead
Never use any - use unknown instead when the type is truly unknown. This forces type checking:
function processData(data: unknown) {
if (typeof data === 'string') {
return data.toUpperCase()
}
if (typeof data === 'number') {
return data.toString()
}
throw new Error('Unsupported data type')
}Generic Types: Write Reusable Code
Use generics to create reusable, type-safe functions and components:
function identity<T>(arg: T): T {
return arg
}
interface ApiResponse<T> {
data: T
status: number
message: string
}
const userResponse: ApiResponse<User> = {
data: { id: 1, name: 'John' },
status: 200,
message: 'Success'
}Utility Types: Leverage Built-in Helpers
TypeScript provides utility types that save time:
// Make all properties optional
type PartialUser = Partial<User>
// Pick specific properties
type UserPreview = Pick<User, 'name' | 'email'>
// Omit specific properties
type UserWithoutId = Omit<User, 'id'>
// Make all properties readonly
type ImmutableUser = Readonly<User>Frequently Asked Questions
Should I use TypeScript for all projects?
For new projects, yes. For existing JavaScript projects, gradual migration is possible. Start with new files and gradually add types to existing code.
What's the difference between interface and type?
Interfaces can be extended and merged, while types can represent unions, intersections, and computed types. For object shapes, interfaces are generally preferred.
How do I handle third-party libraries without types?
Install @types packages (e.g., @types/react) or create your own type declarations in a types folder.
Should I avoid 'any' completely?
Yes, use unknown instead. If you must use any, document why and consider it a temporary solution.
Conclusion
Following these TypeScript best practices will help you write more maintainable, type-safe code that's easier to debug and refactor. These practices have helped me ship more reliable applications with fewer runtime errors.
Need help implementing TypeScript in your project? Book a consultation call to discuss your TypeScript strategy, or view my services for TypeScript development support.
Yassine Ifguisse
Software Developer & Ai SaaS Developer
Building modern web applications with Next.js, React, and TypeScript. Passionate about creating scalable solutions and sharing knowledge through code. I am also a passionate about building ai saas products and services.